Overstory #64 - Homegardens
Tropical homegardens are gaining recognition as highly productive, low input systems. In this edition of The Overstory special guest author Dr. P.K.R. Nair offers an introduction to tropical homegardens.
Home gardening has a long tradition in many tropical countries. Tropical homegardens consist of an assemblage of plants, which may include trees, shrubs, vines, and herbaceous plants, growing in or adjacent to a homestead or home compound. These gardens are planted and maintained by members of the household and their products are intended primarily for household consumption; the gardens also have considerable ornamental value, and they provide shade to people and animals. The word "homegarden" has been used rather loosely to describe diverse practices, from growing vegetables behind houses to complex multistoried systems. It is used here to refer to intimate association of multipurpose trees and shrubs with annual and perennial crops and, invariably livestock within the compounds of individual houses, with the whole crop-tree-animal unit being managed by family labor (Fernandes and Nair, 1986).
Homegardens exemplify many agroforestry characteristics, i.e., the intimate mix of diversified agricultural crops and multipurpose trees fulfills most of the basic needs of the local population while the multistoried configuration and high species diversity of the homegardens help reduce the environmental deterioration commonly associated with monocultural production systems. Moreover, they have been producing sustained yields for centuries in a most resource-efficient way.
Structure of Homegardens
In spite of the very small average size of the management units, homegardens are characterized by a high species diversity and usually 3-4 vertical canopy strata, which results in intimate plant associations. The layered canopy configurations and combination of compatible species are the most conspicuous characteristics of all homegardens. Contrary to the appearance of random arrangement, the gardens are usually carefully structured systems with every component having a specific place and function. The Javanese pekarangan is a clean and carefully tended system surrounding the house, where plants of different heights and architectural types, though not planted in an orderly manner, optimally occupy the available space both horizontally and vertically (Wiersum, 1982; Soemarwoto and Soemarwoto, 1984). The homegardens in the Pacific Islands present a more clearly defined arrangement of species following the orientation and relief characteristics of the watershed. The West African compound farms (Okafor and Fernandes, 1987) are characterized by a four-layer canopy dominated by a large number of tall indigenous fruit trees. An architectural analysis of the canopy reveals a relatively higher percentage of canopy distribution in the upper strata.
In general terms, all homegardens consist of a herbaceous layer near the ground, a tree layer at upper levels, and intermediate layers in between. The lower layer can usually be partitioned into two, with the lowermost (less than 1 m height) dominated by different vegetable and medicinal plants, and the second layer (1-3 m height) being composed of food plants such as cassava, banana, papaya, yam, and so on. The upper tree layer can also be divided in two, consisting of emergent, fully grown timber and fruit trees occupying the uppermost layer of over 25 m height, and medium-sized trees of 10-20 m occupying the next lower layer. The intermediate layer of 3-10 m height is dominated by various fruit trees, some of which would continue to grow taller. This layered structure is never static; the pool of replacement species results in a productive structure which is always dynamic while the overall structure and function of the system are maintained.
Very little has been reported about rooting patterns and configurations in multi-species homegardens. A dynamic equilibrium can be expected with respect to organic matter and plant nutrients on the garden floor due to the continuous addition of leaf litter and its constant removal through decomposition. Consequently, an accumulation of absorbing roots of all species is to be expected at or near the soil surface. At lower depths in the soil, the root distribution of the various species is likely to conform to a vertical configuration roughly proportional to the canopy layers. However, this remains an important aspect for further investigation.
Food production from homegardens
The magnitude and rate of production, as well as the ease and rhythm of maintenance, of the homegarden system depend on its species composition. Although the choice of species is determined to a large extent by environmental and socioeconomic factors, as well as the dietary habits and market demands of the locality, there is a remarkable similarity with respect to species composition among different homegardens in various places, especially with respect to the herbaceous components. This is so because food production is the predominant role of most herbaceous species, and the presence of an overstory requires that the species are shade-tolerant. Thus, tuber crops such as taro, cassava, yam, and sweet potato dominate because they can be grown with relatively little care as understory species in partial shade and yet be expected to yield reasonable levels of carbohydrate-rich produce. Harvesting can be staggered over several weeks depending upon household needs.
A conspicuous trait of the tree-crop component in homegardens is the predominance of fruit trees, and other food-producing trees. Apart from providing a steady supply of various types of edible products, these fruit and food trees are also compatible--both biologically and environmentally--with other components of the system (Nair, 1984). While fruit trees such as guava, rambutan, mango, and mangosteen, and other food-producing trees such as Moringa oleifera and Sesbania grandiflora, dominate the Asian homegardens, indigenous trees that produce leafy vegetables (Pterocarpus spp.), fruit for cooking (Dacroydes edulis), and condiment (Pentaclethra macrophylla), dominate the West African compound farms. Produce from these trees often provides a substantial proportion of the energy and nutritive requirement of the local diet. For example, Terra (1954) and Stoler (1975) reported that Javanese homegardens provided more than 40% of the whole energy requirement of the local farming communities. Soemarwoto and Conway (1991) reported that compared with the rice fields of Java, the homegarden has a greater diversity of production and usually produces a higher net income; in West Java, fish production in homegarden ponds is common, with an income of 2 to 2.5 times that of rice fields in the same area.
Food production is thus the primary function and role of most, if not all, of the homegardens. An aspect of food production in homegardens is the almost continuous production that occurs throughout the year. The combination of crops with different production cycles and rhythms results in a relatively uninterrupted supply of food products. Depending upon the climate and other environmental characteristics, there may be peak and slack seasons for harvesting the various products, but generally there is something to harvest daily from most homegardens. Most of this production is for home consumption, but any marketable surplus can provide a safeguard against future crop failures and security for the interval between the harvests (e.g., rice in Java and Sri Lanka, coffee and maize in Tanzania, coconut and rice in southwestern India, and so on). Additionally, these harvesting and maintenance operations require only a relatively small amount of labor from the members of the family.
Research on homegarden systems
Almost all the homegarden systems have evolved over time under the influence of resource constraints. These include population pressure and consequent reduction in available land and capital. Moreover, physical limitations such as remoteness of the area force the inhabitants to produce most of their basic needs by themselves, and lack of adequate market outlets compel the farmers to produce some portions of everything they need. Scientific attention has seldom focused on improving these traditional systems. Scientists who are not familiar with them do not realize the importance and potential contribution of these systems to the framework of agricultural development. Others, who are under the influence of the traditional outlook of monocultural agriculture or forestry, consider homegardens to be very specialized systems adapted to subsistence land-use and structurally too complex to be suitable for manipulation and improvement. There is a small group of scientists, however, who have conducted detailed investigations of homegardens and who appreciate the value of the systems and the wealth of information they offer regarding the behavior of plants grown in intimate proximity.
Homegardens are very complex systems with a very sophisticated structure and a large number of components. In contrast, researchers are, by and large, specialists in a discipline or a commodity. Farmers who practice homegarden systems are guided, in the absence of a unified set of expert recommendations, by their own perceptions and convictions about species selection, admixture, and management, so that each farm unit is a specialized entity in itself. These contradictions and conditions are the main impediments to coordinated research on homegardens. Yet these important systems deserve more serious attention. A systems approach should provide the basis for research on homegardens, and should include studies of both biological and socioeconomic aspects. There is also an urgent need for quantitative data and practical experimentation.
Fernandes, E.C.M. and Nair, P.K.R. 1986. An evaluation of the structure and function of tropical homegardens. Agricultural Systems 21:279-310.
Landauer, K. and Brazil, M. (eds.). 1990. Tropical Home Gardens. United Nations, University Press, Tokyo, Japan.
Nair, P.K.R. 1984. Fruit Trees in Agroforestry. Working Paper. Environment and Policy Institute, East-West Center, Honolulu, Hawaii, USA.
Okafor, J.C. and Fernandes, E.C.M. 1987. The compound farms of southeastern Nigeria: A predominant agroforestry homegarden system with crops and small livestock. Agroforestry Systems. 5:153-168.
Soemarwoto, 0. and G.R. Conway. 1991. The Javanese homegarden. J. Farming Systems Research-Extension 2(3): 95-117.
Soemarwoto, 0. and Soemarwoto, I. 1984. The Javanese rural ecosystem. In: Rambo, T. and Sajise, E. (eds.), An Introduction to Human Ecology Research on Agricultural Systems in Southeast Asia, pp. 254-287. University of the Philippines, Los Baños, The Philippines.
Stoler, A. 1975. Garden Use and Household Consumption Pattern in a Javanese Village. Ph.D. Dissertation, Columbia University, Department of Anthropology, New York, USA.
Terra, G.T.A. 1954. Mixed-garden horticulture in Java. Malaysian Journal of Tropical Geography 4: 33-43.
Wiersum, K.F. 1982. Tree gardening and taungya in Java: Examples of agroforestry techniques in the humid tropics. Agroforestry Systems 1: 53-70.
The above excerpt is adapted from An Introduction to Agroforestry with kind permission of the author, P.K.R. Nair, and the publisher, Kluwer Academic Publishers.
P.K.R. Nair. 1993. An Introduction to Agroforestry. Kluwer Academic Publishers, Dordrecht, The Netherlands.
About the Author
Dr. P.K.R. Nair is Professor of Agroforestry at the University of Florida, Gainesville, Florida, USA. He has been a founder-scientist at the International Centre for Research and Agroforestry (ICRAF), Nairobi, Kenya for about 10 years. Dr. Nair is a leading world authority and a pioneering researcher and educator in agroforestry.
"Do Tropical Homegardens Elude Science, or Is It the Other Way Round?" by P. K. R. Nair examines strategies for studying ecological and economic unknowns of time-tested multispecies systems.
Tropical Home Gardens: Selected Papers from an International Workshop Held at the Institute of Ecology, Padjadjaran University, Bandung, Indonesia by Kathleen Landauer and Mark Brazil covers the development and management of home garden programs.
Forest Gardening by Robert Hart describes the design of temperate multistory garden plantings which incorporate fruit and nut trees.
Related Editions to The Overstory
- The Overstory #53--Nontimber Forest Products--An Introduction
- The Overstory #51--Expanding Traditional Agroforests
- The Overstory #49--Traditional Pacific Island Agroforestry Systems
- The Overstory #12--Perennial Leaf Vegetables